Field
The present invention relates to integrated micro chip applications. More particularly embodiments of the present invention relate to an RFID tag with an integrated micro chip.
Background Information
Radio frequency identification (RFID) is a manner of identifying objects with a wireless communication protocol. The technology can be used to identify, track, sort or detect a wide variety of objects. An RFID system generally includes an RFID tag and a reader. Passive RFID tags include an integrated circuit or chip and an antenna, and are powered by an electromagnetic field provided by the reader. The available power from the reader reduces rapidly with distance and is generally regulated resulting in limited communication distances up to several meters. Passive RFID tags can be operated over the entire frequency range available to RFID systems including low frequency (LF; <300 kHz; 125 kHz primary frequency), high frequency (HF; 3 MHz-30 MHz; primary frequency 13.56 MHz), ultra-high frequency (UHF; 860 MHz-950 MHz; 915 MHz primary frequency in United States, 950 MHz primary frequency in Japan, 868 MHz primary frequency in Europe), and microwave (2.45 GHz-5.8 GHz; 5.8 GHz primary frequency). Active RFID tags include an integrated circuit or chip, an antenna, and a built-in power supply, such as a battery or solar cell to provide voltage to the chip. As a result the electric field detected by the antenna can be much weaker than the electric field that would be required to power a passive RFID tag. This allows communication with the reader at distances of over several kilometers. Active RFID tags most often are operated at the UHF and microwave frequencies.
A variety of characteristics are used to characterize RFID tags such as their capability to read and write data, memory capacity, operating frequency, operating range (distance), and security requirements. At the low-end spectrum of RFID tag functionality, are included read-only passive RFID tags that store a small amount of data. At the high-end spectrum of RFID tag functionality, are included read-write active RFID tags that may additionally include a microprocessor to facilitate more complex logic.
RFID tags generally receive energy and communicate with the reader using two methods. In one manner, the RFID tag communicates with the reader using magnetic field, also termed near field, inductive coupling in which the tag inductively couples to the magnetic field circulating around the reader antenna. The RFID tag associated with near field inductive coupling often includes a coiled antenna that operates at the LF or HF frequencies. A typical read range for passive RFID tags with LF and HF antennas is less than 0.5 meters and approximately 1 meter, respectively. In another manner, the RFID tag couples to the electric field, also termed far field, of the reader and communicates to the reader using backscatter. The RFID tag associated with far field coupling often includes a dipolar antenna that operates at the UHF or microwave frequencies. A typical read range for passive RFID tags with UHF and microwave antennas is approximately 4-5 meters and approximately 1 meter, respectively.
Other related characteristics of RFID tags are cost and reliability. The type of materials and assembly methods used to package RFID tags impact the final cost, and to some extent their performance. A typical RFID tag assembly process includes forming a conductive antenna on a substrate, connecting the chip to the antenna, and forming a protective overlay material over the antenna and chip. Chip connection is typically performed using wire bonding, flip chip, or cut clamp technology (CCT). The protective overlay is typically a polyvinyl chloride (PVC) lamination, epoxy resin, or adhesive. Chip size is also a factor in overall cost.